Display Driving Circuit Amplitude and Pulse Width Control
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Solution Overview
Problem
Display devices using light emitting elements face challenges in accurately controlling gray levels due to the non-linear relationship between the pulse amplitude of the driving current and the brightness of the light emitting elements, leading to inaccuracies in displaying intended gray levels.
Innovation Solution
The implementation of a display device with driving circuits that include a first transistor, a second transistor, a reset circuit, and control circuits to adjust the pulse amplitude and pulse width of the driving current, utilizing sweep signals to control the phase and timing of the current, allowing for more precise control of the light emitting elements' brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If only pulse amplitude of driving current is controlled, then the control method is simple, but the gray level display accuracy is poor due to non-linear relationship between current amplitude and brightness
Solution Approach 1:
The patent segments the driving current control into two independent dimensions: pulse amplitude control (via first transistor) and pulse width control (via second transistor). This segmentation allows the system to overcome the non-linear relationship between amplitude and brightness by introducing pulse width as an additional control variable, thereby achieving accurate gray level display while maintaining control simplicity.
Solution Approach 2:
The patent transitions from one-dimensional control (amplitude only) to two-dimensional control by adding pulse width modulation. The first transistor controls amplitude while the second transistor controls pulse width, creating a dual-dimensional control space that enables precise gray level representation despite the non-linear amplitude-brightness relationship.
2Manufacturing precision
If dual transistor control circuit is used to adjust both pulse amplitude and pulse width, then the gray level control accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent implements multi-functionality by having the second transistor serve multiple purposes: it controls pulse width modulation and also responds to sweep signals for phase adjustment. This universal approach allows accurate gray level control through pulse width modulation while the sweep signal integration provides additional timing control without requiring separate dedicated circuits.
Solution Approach 2:
The patent merges the gray level control function and the timing/phase control function into a unified dual-transistor architecture. The first transistor handles amplitude for gray level, while the second transistor handles both pulse width for gray level and phase timing through sweep signals, consolidating multiple control functions into an integrated circuit structure.
3Measurement precision
If sweep signals are used to control phase and timing of driving current, then the timing precision is improved, but the control circuit complexity increases
Solution Approach 1:
The patent uses sweep signals as intermediary control inputs that mediate between the driving circuit and the light emitting element timing. The sweep signals serve as external timing references that the second transistor uses to adjust phase and timing, providing precise timing control while keeping the internal circuit structure relatively simple through external signal coordination.
Data Source
AI summary
A display device includes a multiple of light-emitting elements and a multiple of driving circuits. Each of the multiple of driving circuits is configured to generate a driving current flowing through one of the multiple of light-emitting elements. Each of the multiple of driving circuits includes a first transistor, a second transistor, a reset circuit, a first control circuit and a second control circuit. The driving current flows from a first system high voltage terminal through the first transistor, the second transistor and one of the multiple of light-emitting elements to a system low voltage terminal. The first control circuit is configured to control the first transistor to modulate pulse amplitude of the driving current. The second control circuit is configured to control the second transistor to modulate pulse width of the driving current.